Sink Overflow Drain?

Soap suds are coming out of the overflow area of my bathroom sink. I exclusively wash my hands in this sink. I do wash my hands frequently and perhaps this has caused some residual soap scum to remain in there. Is this a problem? Will the soap get into the pipes for other sinks, like the kitchen sink?
When I run the water for a bit, the soap stops coming. However, if I use a tiny bit of soap, then the suds start coming out of the overflow area again. I am concerned, being that I am pregnant, that the vent is clogged and sewer gases are being released. Is this a valid concern? And if so, how bad is that? Is it bad that I've been using this sink to wash my hands if this is the case? Have I essentially contaminated everything in my home? I have also read that there is a lot of bacteria in the sink overflow. I just want to make sure that nothing detrimental has been caused by this. If anyone could help me, I would greatly appreciate it.

OK, no problem. Your drain is just getting partially clogged with the usual bathroom soap scum, hair, oils, makeup, etc.
Easy fix.
Get a good non-caustic enzyme-based drain cleaner like DrainCare. Run or pour warm water into the sink overflow hole and the sink drain (see instructions on jug), pour in a liberal amount of DrainCare, let it eat overnight, and then flush it all down with very hot water the next morning. I always start that off with a kettle of boiling water, and then just let the hot water run a while.
Enzyme-based drain cleaner is non-toxic, and won't harm you or your sink or fixtures, but it WILL eat out and dissolve the organic gunk build-up around the inside of your pipe and sink. Sometimes the gunk, if it has built up badly, dissolves into a gel-like blob, and you may have to stop up the overflow hole with your thumb, and plunge the sink drain a bit to get it going, but it will go. You also can sanitize your overflow with a bit of regular bleach poured into the hole.
I coincidentally did one of our bathroom sinks just like this with DrainCare a week or so ago for the same reason. Works like a charm.
Good luck!
Mike